docs: def log(x, base=None):
      """ log(x, base=e)
      Logarithmic function.
      """
      _math = infer_math(x)
      if base is None:
          return _math.log(x)
      elif _math == math:
          return _math.log(x, base)
      else:
          # numpy has no option to set a base
          return _math.log(x) / _math.log(base)