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_inline_function():
    x = symbols('x')
    g = implemented_function('g', Lambda(x, 2*x))
    assert ccode(g(x)) == "2*x"
    g = implemented_function('g', Lambda(x, 2*x/Catalan))
    assert ccode(
        g(x)) == "double const Catalan = %s;\n2*x/Catalan" % Catalan.n()
    A = IndexedBase('A')
    i = Idx('i', symbols('n', integer=True))
    g = implemented_function('g', Lambda(x, x*(1 + x)*(2 + x)))
    assert ccode(g(A[i]), assign_to=A[i]) == (
        "for (int i=0; i<n; i++){\n"
        "   A[i] = (A[i] + 1)*(A[i] + 2)*A[i];\n"
        "}"
    )