Process a python file.

def process_python(self, path):
        """Process a python file."""
        (pylint_stdout, pylint_stderr) = epylint.py_run(
            ' '.join([str(path)] + self.pylint_opts), return_std=True)
        emap = {}
        print(pylint_stderr.read())
        for line in pylint_stdout:
            sys.stderr.write(line)
            key = line.split(':')[-1].split('(')[0].strip()
            if key not in self.pylint_cats:
                continue
            if key not in emap:
                emap[key] = 1
            else:
                emap[key] += 1
        sys.stderr.write('\n')
        self.python_map[str(path)] = emap