code: def FloatGreaterThanEqualToZero(x):
      
      try:
          x = float(x)
      except:
          raise ValueError("%r not float greater than or equal to zero" % x)
      if x >= 0:
          return x
      else:
          raise ValueError("%r not float greater than or equal to zero" % x)
docs: If *x* is a float >= 0, returns it, otherwise raises and error.
  
      >>> print('%.1f' % FloatGreaterThanEqualToZero('1.5'))
      1.5
  
      >>> print('%.1f' % FloatGreaterThanEqualToZero('-1.1'))
      Traceback (most recent call last):
         ...
      ValueError: -1.1 not float greater than or equal to zero