See the Wikipedia page for Box-drawing characters.
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│ │ │
├ ─ ┼ ─ ┤
│ │ │
└ ─ ┴ ─ ┘
━┃┄┆┅┇┈┊┉┋╌╍╎╏╴╵╶╷╸╹╺╻╼╽╾╿
┍┑┎┒┏┓
┕┙┖┚┗┛
┝┞┟┠┡┢┣┥┦┧┨┩┪┫
┭┮┯┰┱┲┳┵┶┷┸┹┺┻
┽┾┿╀╁╂╃╄╅╆╇╈╉╊╋
═║
╒╓╔╕╖╗
╘╙╚╛╜╝
╞╟╠╡╢╣╤╥╦╧╨╩╪╫╬
╭╮
╰╯
╱ ╲ ╳