code: def from_string(cls, s):
          
          # Extract num and unit string.
          s = s.strip()
          for i, char in enumerate(s):
              if char.isalpha() or char.isspace():
                  break
          else:
              raise Exception("Unit is missing in string %s" % s)
          num, unit = float(s[:i]), s[i:]
  
          # Find unit type (set it to None if it cannot be detected)
          for unit_type, d in BASE_UNITS.items():
              if unit in d:
                  break
          else:
              unit_type = None
  
          return cls(num, unit, unit_type=unit_type)
docs: Initialize a FloatWithUnit from a string. Example Memory.from_string("1. Mb")