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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 get_auth_bearer(self):
 """return the bearer token in the authorization header if it exists"""

        access_token = ''
        auth_header = self.get_header('authorization')
        if auth_header:
            m = re.search(r"^Bearer\s+(\S+)$", auth_header, re.I)
            if m: access_token = m.group(1)

        return access_token