code: def mul(left, right):
      
      from .mv_mul import MvMul
      length = max(left, right)
      if length == 1:
          return Mul(left, right)
      return MvMul(left, right)
docs: Distribution multiplication.
  
      Args:
          left (Dist, numpy.ndarray) : left hand side.
          right (Dist, numpy.ndarray) : right hand side.