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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 header(self, name, default=None):
 """ Returns the value of the HTTP header identified by `name`. """

        wsgi_header = "HTTP_{0}".format(name.upper())

        try:
            return self.env_raw[wsgi_header]
        except KeyError:
            return default