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_impl(A, B):
            df = pd.DataFrame({'A': A, 'B': B})
            df2 = df.groupby('A', as_index=False)['B'].sum()
            # TODO: fix handling of df setitem to force match of array dists
            # probably with a new node that is appended to the end of basic block
            # df2['C'] = np.full(len(df2.B), 3, np.int8)
            # TODO: full_like for Series
            df2['C'] = np.full_like(df2.B.values, 3, np.int8)
            return df2