code: def to_python(self, value):
          "Normalize data to a list of strings."
          # Return None if no input was given.
          if not value:
              return []
          return [v.strip() for v in value.splitlines() if v != ""f to_python(self, value):
          "Normalize data to a list of strings."
          # Return None if no input was given.
          if not value:
              return []
          return [v.strip() for v in value.splitlines() if v != ""]
docs: Normalize data to a list of strings.