diff --git a/figures/tgate.svg b/figures/tgate.svg
new file mode 100644
index 0000000..6d09039
--- /dev/null
+++ b/figures/tgate.svg
@@ -0,0 +1,54 @@
+<?xml version='1.0' encoding='UTF-8'?>
+<!-- This file was generated by dvisvgm 3.0.3 -->
+<svg version='1.1' xmlns='http://www.w3.org/2000/svg' xmlns:xlink='http://www.w3.org/1999/xlink' width='102.582852pt' height='107.062782pt' viewBox='-63.698806 -63.698286 102.582852 107.062782'>
+<defs>
+<font id='cmr10' horiz-adv-x='0'>
+<font-face font-family='cmr10' units-per-em='1000' ascent='750' descent='250'/>
+<glyph unicode='¯' horiz-adv-x='500' vert-adv-y='500' glyph-name='macron' d='M430 559V590H69V559H430Z'/>
+</font>
+<font id='cmmi10' horiz-adv-x='0'>
+<font-face font-family='cmmi10' units-per-em='1000' ascent='750' descent='250'/>
+<glyph unicode='A' horiz-adv-x='750' vert-adv-y='750' glyph-name='A' d='M179 115C139 48 100 34 56 31C44 30 35 30 35 11C35 5 40 0 48 0C75 0 106 3 134 3C167 3 202 0 234 0C240 0 253 0 253 19C253 30 244 31 237 31C214 33 190 41 190 66C190 78 196 89 204 103L280 231H531C533 210 547 74 547 64C547 34 495 31 475 31C461 31 451 31 451 11C451 0 463 0 465 0C506 0 549 3 590 3C615 3 678 0 703 0C709 0 721 0 721 20C721 31 711 31 698 31C636 31 636 38 633 67L572 692C570 712 570 716 553 716C537 716 533 709 527 699L179 115ZM299 262L496 592L528 262H299Z'/>
+<glyph unicode='i' horiz-adv-x='344' vert-adv-y='344' glyph-name='i' d='M284 625C284 645 270 661 247 661C220 661 193 635 193 608C193 589 207 572 231 572C254 572 284 595 284 625ZM208 249C220 278 220 280 230 307C238 327 243 341 243 360C243 405 211 442 161 442C67 442 29 297 29 288C29 278 39 278 41 278C51 278 52 280 57 296C84 390 124 420 158 420C166 420 183 420 183 388C183 367 176 346 172 336C164 310 119 194 103 151C93 125 80 92 80 71C80 24 114-11 162-11C256-11 293 134 293 143C293 153 284 153 281 153C271 153 271 150 266 135C248 72 215 11 164 11C147 11 140 21 140 44C140 69 146 83 169 144L208 249Z'/>
+<glyph unicode='n' horiz-adv-x='600' vert-adv-y='600' glyph-name='n' d='M88 59C85 44 79 21 79 16C79-2 93-11 108-11C120-11 138-3 145 17C146 19 158 66 164 91L186 181C192 203 198 225 203 248C207 265 215 294 216 298C231 329 284 420 379 420C424 420 433 383 433 350C433 288 384 160 368 117C359 94 358 82 358 71C358 24 393-11 440-11C534-11 571 135 571 143C571 153 562 153 559 153C549 153 549 150 544 135C524 67 491 11 442 11C425 11 418 21 418 44C418 69 427 93 436 115C455 168 497 278 497 335C497 402 454 442 382 442C292 442 243 378 226 355C221 411 180 442 134 442S69 403 59 385C43 351 29 292 29 288C29 278 39 278 41 278C51 278 52 279 58 301C75 372 95 420 131 420C151 420 162 407 162 374C162 353 159 342 146 290L88 59Z'/>
+<glyph unicode='o' horiz-adv-x='484' vert-adv-y='484' glyph-name='o' d='M469 273C469 377 399 442 309 442C175 442 41 300 41 158C41 59 108-11 201-11C334-11 469 127 469 273ZM202 11C159 11 115 42 115 120C115 169 141 277 173 328C223 405 280 420 308 420C366 420 396 372 396 312C396 273 376 168 338 103C303 45 248 11 202 11Z'/>
+<glyph unicode='t' horiz-adv-x='361' vert-adv-y='361' glyph-name='t' d='M206 400H300C320 400 330 400 330 420C330 431 320 431 302 431H214C250 573 255 593 255 599C255 616 243 626 226 626C223 626 195 625 186 590L147 431H53C33 431 23 431 23 412C23 400 31 400 51 400H139C67 116 63 99 63 81C63 27 101-11 155-11C257-11 314 135 314 143C314 153 306 153 302 153C293 153 292 150 287 139C244 35 191 11 157 11C136 11 126 24 126 57C126 81 128 88 132 105L206 400Z'/>
+<glyph unicode='u' horiz-adv-x='572' vert-adv-y='572' glyph-name='u' d='M350 56C361 15 396-11 439-11C474-11 497 12 513 44C530 80 543 141 543 143C543 153 534 153 531 153C521 153 520 149 517 135C503 79 484 11 442 11C421 11 411 24 411 57C411 79 423 126 431 161L459 269C462 284 472 322 476 337C481 360 491 398 491 404C491 422 477 431 462 431C457 431 431 430 423 396C404 323 360 148 348 95C347 91 307 11 234 11C182 11 172 56 172 93C172 149 200 228 226 297C238 327 243 341 243 360C243 405 211 442 161 442C66 442 29 297 29 288C29 278 39 278 41 278C51 278 52 280 57 296C82 383 120 420 158 420C167 420 183 419 183 387C183 363 172 334 166 319C129 220 108 158 108 109C108 14 177-11 231-11C297-11 333 34 350 56Z'/>
+</font>
+</defs>
+<style type='text/css'>
+<![CDATA[text.f0 {font-family:cmmi10;font-size:9.96264px}
+text.f1 {font-family:cmr10;font-size:9.96264px}
+]]>
+</style>
+<g id='page1'>
+<path d='M7.2617-17.1367H-7.125V-31.0273' stroke='#000' fill='none' stroke-width='.3985'/>
+<path d='M-3.8516-31.0273H-25.6797M-7.125-34.3594H-22.40625' stroke='#000' fill='none' stroke-width='.797'/>
+<path d='M-22.40625-31.0273V-17.1367H-36.793' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<path d='M-14.765625-34.3594V-45.117187' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<path d='M-14.765625-34.3594C-13.890625-34.3594-13.17969-35.07031-13.17969-35.94922C-13.17969-36.82422-13.890625-37.53516-14.765625-37.53516C-15.644531-37.53516-16.35156-36.82422-16.35156-35.94922C-16.35156-35.07031-15.644531-34.3594-14.765625-34.3594Z'/>
+<path d='M-14.765625-34.3594C-13.890625-34.3594-13.17969-35.07031-13.17969-35.94922C-13.17969-36.82422-13.890625-37.53516-14.765625-37.53516C-15.644531-37.53516-16.35156-36.82422-16.35156-35.94922C-16.35156-35.07031-15.644531-34.3594-14.765625-34.3594Z' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<path d='M-36.793-1.8281H-22.40625V12.0586M-7.125 12.0586V-1.8281H7.2617' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<path d='M-25.6797 12.0586H-3.8516M-22.40625 15.3945H-7.125' stroke='#000' fill='none' stroke-width='.797' stroke-miterlimit='10'/>
+<path d='M-14.765625 15.3945V26.1484' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<path d='M-36.5937-17.1367V-1.8281' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<path d='M7.0625-17.1367V-1.8281' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<path d='M7.0625-9.4844H14.1484M14.1484-9.4844H21.2344' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<path d='M22.8203-9.4844C22.8203-10.3594 22.1094-11.0703 21.2344-11.0703S19.6484-10.3594 19.6484-9.4844C19.6484-8.6055 20.3594-7.8945 21.2344-7.8945S22.8203-8.6055 22.8203-9.4844Z'/>
+<path d='M22.8203-9.4844C22.8203-10.3594 22.1094-11.0703 21.2344-11.0703S19.6484-10.3594 19.6484-9.4844C19.6484-8.6055 20.3594-7.8945 21.2344-7.8945S22.8203-8.6055 22.8203-9.4844Z' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<text class='f0' x='-14.766206' y='-44.916904' transform='matrix(1 0 0 1 39.5203 38.49744)'>out</text>
+<path d='M-36.5937-9.4844H-43.6797M-43.6797-9.4844H-50.7656' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<path d='M-49.1797-9.4844C-49.1797-10.3594-49.8906-11.0703-50.7656-11.0703C-51.6445-11.0703-52.3555-10.3594-52.3555-9.4844C-52.3555-8.6055-51.6445-7.8945-50.7656-7.8945C-49.8906-7.8945-49.1797-8.6055-49.1797-9.4844Z'/>
+<path d='M-49.1797-9.4844C-49.1797-10.3594-49.8906-11.0703-50.7656-11.0703C-51.6445-11.0703-52.3555-10.3594-52.3555-9.4844C-52.3555-8.6055-51.6445-7.8945-50.7656-7.8945C-49.8906-7.8945-49.1797-8.6055-49.1797-9.4844Z' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<text class='f0' x='-14.766206' y='-44.916904' transform='matrix(1 0 0 1 -48.9326 38.71884)'>in</text>
+<path d='M-14.765625-44.917968V-48.46094M-14.765625-48.46094V-52.00391' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<path d='M-13.17969-52.00391C-13.17969-52.87891-13.890625-53.58984-14.765625-53.58984C-15.644531-53.58984-16.35156-52.87891-16.35156-52.00391S-15.644531-50.41797-14.765625-50.41797C-13.890625-50.41797-13.17969-51.12891-13.17969-52.00391Z'/>
+<path d='M-13.17969-52.00391C-13.17969-52.87891-13.890625-53.58984-14.765625-53.58984C-15.644531-53.58984-16.35156-52.87891-16.35156-52.00391S-15.644531-50.41797-14.765625-50.41797C-13.890625-50.41797-13.17969-51.12891-13.17969-52.00391Z' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<text class='f1' x='-12.137133' y='-47.435231' transform='matrix(1 0 0 1 -3.736 -10.6065)'>¯</text>
+<text class='f0' x='-14.766206' y='-44.916904' transform='matrix(1 0 0 1 -3.736 -10.6065)'>A</text>
+<path d='M-14.765625 25.9492V29.4922M-14.765625 29.4922V33.0352' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<path d='M-13.17969 33.0352C-13.17969 32.1602-13.890625 31.4492-14.765625 31.4492C-15.644531 31.4492-16.35156 32.1602-16.35156 33.0352C-16.35156 33.9141-15.644531 34.625-14.765625 34.625C-13.890625 34.625-13.17969 33.9141-13.17969 33.0352Z'/>
+<path d='M-13.17969 33.0352C-13.17969 32.1602-13.890625 31.4492-14.765625 31.4492C-15.644531 31.4492-16.35156 32.1602-16.35156 33.0352C-16.35156 33.9141-15.644531 34.625-14.765625 34.625C-13.890625 34.625-13.17969 33.9141-13.17969 33.0352Z' stroke='#000' fill='none' stroke-width='.3985' stroke-miterlimit='10'/>
+<text class='f0' x='-14.766206' y='-44.916904' transform='matrix(1 0 0 1 -3.736 88.2814)'>A</text>
+</g>
+</svg>
\ No newline at end of file