Draw histogram of the input series using matplotlib.

    Parameters
    ----------
    by : object, optional
        If passed, then used to form histograms for separate groups
    ax : matplotlib axis object
        If not passed, uses gca()
    grid : bool, default True
        Whether to show axis grid lines
    xlabelsize : int, default None
        If specified changes the x-axis label size
    xrot : float, default None
        rotation of x axis labels
    ylabelsize : int, default None
        If specified changes the y-axis label size
    yrot : float, default None
        rotation of y axis labels
    figsize : tuple, default None
        figure size in inches by default
    bins : integer or sequence, default 10
        Number of histogram bins to be used. If an integer is given, bins + 1
        bin edges are calculated and returned. If bins is a sequence, gives
        bin edges, including left edge of first bin and right edge of last
        bin. In this case, bins is returned unmodified.
    bins : integer, default 10
        Number of histogram bins to be used
    `**kwds` : keywords
        To be passed to the actual plotting function

    See Also
    --------
    matplotlib.axes.Axes.hist : Plot a histogram using matplotlib.

def hist_series(self, by=None, ax=None, grid=True, xlabelsize=None,
                xrot=None, ylabelsize=None, yrot=None, figsize=None,
                bins=10, **kwds):
    """
    Draw histogram of the input series using matplotlib.

    Parameters
    ----------
    by : object, optional
        If passed, then used to form histograms for separate groups
    ax : matplotlib axis object
        If not passed, uses gca()
    grid : bool, default True
        Whether to show axis grid lines
    xlabelsize : int, default None
        If specified changes the x-axis label size
    xrot : float, default None
        rotation of x axis labels
    ylabelsize : int, default None
        If specified changes the y-axis label size
    yrot : float, default None
        rotation of y axis labels
    figsize : tuple, default None
        figure size in inches by default
    bins : integer or sequence, default 10
        Number of histogram bins to be used. If an integer is given, bins + 1
        bin edges are calculated and returned. If bins is a sequence, gives
        bin edges, including left edge of first bin and right edge of last
        bin. In this case, bins is returned unmodified.
    bins : integer, default 10
        Number of histogram bins to be used
    `**kwds` : keywords
        To be passed to the actual plotting function

    See Also
    --------
    matplotlib.axes.Axes.hist : Plot a histogram using matplotlib.
    """
    import matplotlib.pyplot as plt

    if by is None:
        if kwds.get('layout', None) is not None:
            raise ValueError("The 'layout' keyword is not supported when "
                             "'by' is None")
        # hack until the plotting interface is a bit more unified
        fig = kwds.pop('figure', plt.gcf() if plt.get_fignums() else
                       plt.figure(figsize=figsize))
        if (figsize is not None and tuple(figsize) !=
                tuple(fig.get_size_inches())):
            fig.set_size_inches(*figsize, forward=True)
        if ax is None:
            ax = fig.gca()
        elif ax.get_figure() != fig:
            raise AssertionError('passed axis not bound to passed figure')
        values = self.dropna().values

        ax.hist(values, bins=bins, **kwds)
        ax.grid(grid)
        axes = np.array([ax])

        _set_ticks_props(axes, xlabelsize=xlabelsize, xrot=xrot,
                         ylabelsize=ylabelsize, yrot=yrot)

    else:
        if 'figure' in kwds:
            raise ValueError("Cannot pass 'figure' when using the "
                             "'by' argument, since a new 'Figure' instance "
                             "will be created")
        axes = grouped_hist(self, by=by, ax=ax, grid=grid, figsize=figsize,
                            bins=bins, xlabelsize=xlabelsize, xrot=xrot,
                            ylabelsize=ylabelsize, yrot=yrot, **kwds)

    if hasattr(axes, 'ndim'):
        if axes.ndim == 1 and len(axes) == 1:
            return axes[0]
    return axes