docs: def isnumerical(x):
          # type: (...) -> bool
          """Check the input x is numerical or not.
  
          Examples:
              >>> MathClass.isnumerical('78')
              True
              >>> MathClass.isnumerical('1.e-5')
              True
              >>> MathClass.isnumerical(None)
              False
              >>> MathClass.isnumerical('a1.2')
              False
              >>> MathClass.isnumerical(['1.2'])
              False
              >>> MathClass.isnumerical(numpy.float64(1.2))
              True
  
          """
          try:
              xx = float(x)
          except TypeError:
              return False
          except ValueError:
              return False
          except Exception:
              return False
          else:
              return True