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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 parse_string(self):
 """Parse a regular unquoted string from the token stream."""

        aliased_value = LITERAL_ALIASES.get(self.current_token.value.lower())
        if aliased_value is not None:
            return aliased_value
        return String(self.current_token.value)