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 transientsc(bch, title=''):
    """creates a transient short circuit plot"""
    cols = 1
    rows = 2
    htitle = 1.5 if title else 0
    fig, ax = plt.subplots(nrows=rows, ncols=cols,
                           figsize=(10, 3*rows + htitle))
    if title:
        fig.suptitle(title, fontsize=16)

    row = 1
    plt.subplot(rows, cols, row)
    ax = plt.gca()
    ax.set_title('Currents / A')
    ax.grid(True)
    for i in ('ia', 'ib', 'ic'):
        ax.plot(bch.scData['time'], bch.scData[i], label=i)
    ax.set_xlabel('Time / s')
    ax.legend()

    row = 2
    plt.subplot(rows, cols, row)
    ax = plt.gca()
    ax.set_title('Torque / Nm')
    ax.grid(True)
    ax.plot(bch.scData['time'], bch.scData['torque'])
    ax.set_xlabel('Time / s')

    fig.tight_layout(h_pad=2)
    if title:
        fig.subplots_adjust(top=0.92)