def generate(input_str):
''' Parses an input string and returns another one
containing the generated program skeleton.
'''
HEADER, L, ENDCODE = parser.parse(input_str)
result = 'from skel import Grammar\n'
if HEADER is not None:
result += HEADER + '\n'
result = result + """
def generate(self):
"""
result = ''
grammar = Grammar(Parser.START_SYMBOL)
if L:
for T in L:
grammar.addRule(T)
result += grammar.generate(Parser.START_SYMBOL)
if ENDCODE is not None:
result += ENDCODE + '\n'
return result
