class A:
    def m(self):
        'line1' \
        'line2' \
        'line3'
        print(1)

a = A()
a.m()
print(a.m.__doc__)

def fix_doc_strings(cls):
    for name, method in cls.__dict__.iteritems():
        if callable(method):
            doc_str = " ".join(map(str.strip, method.__doc__.splitlines()))
            method.__doc__ = doc_str
    return cls