def load(self, requirements_file=None):
        """Load or reload requirements from a requirements.txt file.

        :param requirements_file: if not given, the filename used from
            initialization will be read again.
        """
        if requirements_file is None:
            requirements_file = self.filename
            if requirements_file is None:
                raise ValueError("no filename provided")
        elif isinstance(requirements_file, text_type):
            requirements_file = Path(requirements_file)
        self.clear()
        with requirements_file.open() as f:
            self.loads(f.read())

        if isinstance(requirements_file, (text_type, Path)):
            self.filename = requirements_file
def test_ccode_constants_other():
    assert ccode(2*GoldenRatio) == "double const GoldenRatio = 1.61803398874989;\n2*GoldenRatio"
    assert ccode(
        2*Catalan) == "double const Catalan = 0.915965594177219;\n2*Catalan"
    assert ccode(2*EulerGamma) == "double const EulerGamma = 0.577215664901533;\n2*EulerGamma"