Loads as many files as the number of pages

        Args:
            fobjs: [filename or DataFile obj, ...]

def load_many(self, fobjs=None):
        """Loads as many files as the number of pages

        Args:
            fobjs: [filename or DataFile obj, ...]"""
        if fobjs is not None:
            # tolerance
            if not hasattr(fobjs, "__iter__"):
                fobjs = [fobjs]

            for index, (fobj, page) in enumerate(zip(fobjs, self.pages)):
                if fobj is None:
                    continue
                elif isinstance(fobj, ft.DataFile):
                    self.load(fobj, index)
                elif isinstance(fobj, str):
                    self.load_filename(fobj, index)
                else:
                    raise TypeError("Invalid object of class '{}'".format(fobj.__class__.__name__))