'Create a new PdfPages object.
Parameters
filename : str
Plots using :meth:`PdfPages.savefig` will be written to a file at
this location. The file is opened at once and any older file with
the same name is overwritten.
keep_empty : bool, optional
If set to False, then empty pdf files will be deleted automatically
when closed.
metadata : dictionary, optional
Information dictionary object (see PDF reference section 10.2.1
\'Document Information Dictionary\'), e.g.:
`{\'Creator\': \'My software\', \'Author\': \'Me\',
\'Title\': \'Awesome fig\'}`
The standard keys are `\'Title\'`, `\'Author\'`, `\'Subject\'`,
`\'Keywords\'`, `\'Creator\'`, `\'Producer\'`, `\'CreationDate\'`,
`\'ModDate\'`, and `\'Trapped\'`. Values have been predefined
for `\'Creator\'`, `\'Producer\'` and `\'CreationDate\'`. They
can be removed by setting them to `None`.'

def __init__(self, filename, keep_empty=True, metadata=None):

    self._file = PdfFile(filename, metadata=metadata)
    self.keep_empty = keep_empty
