'Writes the interface to a header file.
This file contains all the function declarations.
Parameters
routines : list
A list of Routine instances.
f : file-like
Where to write the file.
prefix : string
The filename prefix.
header : bool, optional
When True, a header comment is included on top of each source
file.  [default : True]
empty : bool, optional
When True, empty lines are included to structure the source
files.  [default : True]'

def dump_h(self, routines, f, prefix, header=True, empty=True):

    if header:
        print(''.join(self._get_header()), file=f)
    if empty:
        print(file=f)
    for routine in routines:
        prototype = self.get_interface(routine)
        f.write(prototype)
    if empty:
        print(file=f)
