<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def unmarshal(self, value, custom_formatters=None, strict=True):
 """Unmarshal parameter from the value."""

        if self.deprecated:
            warnings.warn("The schema is deprecated", DeprecationWarning)

        casted = self.cast(value, custom_formatters=custom_formatters, strict=strict)

        if casted is None and not self.required:
            return None

        if self.enum and casted not in self.enum:
            raise InvalidSchemaValue(
                "Value {value} not in enum choices: {type}", value, self.enum)

        return casted