    def pop_float(self, key: str, default: Any = DEFAULT) -> Optional[float]:
        """
        Performs a pop and coerces to a float.
        """
        value = self.pop(key, default)
        if value is None:
            return None
        else:
            return float(value)
Performs a pop and coerces to a float.
allennlp/common/params.py