code: def ttvar(name, index=None):
      
      bvar = boolfunc.var(name, index)
      try:
          var = _VARS[bvar.uniqid]
      except KeyError:
          var = _VARS[bvar.uniqid] = TTVariable(bvar)
      return var
docs: Return a TruthTable variable.
  
      Parameters
      ----------
      name : str
          The variable's identifier string.
      index : int or tuple[int], optional
          One or more integer suffixes for variables that are part of a
          multi-dimensional bit-vector, eg x[1], x[1][2][3]