docs: def sendcontrol(self, char):
          '''Helper method that wraps send() with mnemonic access for sending control
          character to the child (such as Ctrl-C or Ctrl-D).  For example, to send
          Ctrl-G (ASCII 7, bell, '\a')::
              child.sendcontrol('g')
          See also, sendintr() and sendeof().
          '''
          char = char.lower()
          a = ord(char)
          if 97 <= a <= 122:
              a = a - ord('a') + 1
              byte = bytes([a])
              return self.pty.write(byte.decode('utf-8')), byte
          d = {'@': 0, '`': 0,
              '[': 27, '{': 27,
              '\\': 28, '|': 28,
              ']': 29, '}': 29,
              '^': 30, '~': 30,
              '_': 31,
              '?': 127}
          if char not in d:
              return 0, b''
  
          byte = bytes([d[char]])
          return self.pty.write(byte.decode('utf-8')), byte