'Set the font size.  Either an relative value of \'xx-small\',
\'x-small\', \'small\', \'medium\', \'large\', \'x-large\', \'xx-large\'
or an absolute font size, e.g., 12.'

def set_size(self, size):

    if (size is None):
        size = rcParams[u'font.size']
    try:
        size = float(size)
    except ValueError:
        try:
            scale = font_scalings[size]
        except KeyError:
            raise ValueError((u'Size    is    invalid.    Valid    font    size    are    ' + u',    '.join(map(str, font_scalings))))
        else:
            size = (scale * FontManager.get_default_size())
    self._size = size
