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_Indexed():
    from sympy.tensor import IndexedBase, Idx
    from sympy import symbols
    n, m, o = symbols('n m o', integer=True)
    i, j, k = Idx('i', n), Idx('j', m), Idx('k', o)
    p = CCodePrinter()
    p._not_c = set()

    x = IndexedBase('x')[j]
    assert p._print_Indexed(x) == 'x[j]'
    A = IndexedBase('A')[i, j]
    assert p._print_Indexed(A) == 'A[%s]' % (m*i+j)
    B = IndexedBase('B')[i, j, k]
    assert p._print_Indexed(B) == 'B[%s]' % (i*o*m+j*o+k)

    assert p._not_c == set()