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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def username(self):
 """Loking for username in user's input and config file"""

        if len(self._inp_username.value.strip()) == 0: # if username provided by user
            if not self.hostname is None:
                config = parse_sshconfig(self.hostname)
                if 'user' in config: # if username is present in the config file
                    return config['user']
            else:
                return None
        else:
            return self._inp_username.value