parameters: (self, http_request)
return_statement: return headers_to_sign
docstring: Select the headers from the request that need to be included
          in the StringToSign.
docstring_summary: Select the headers from the request that need to be included
          in the StringToSign.
docstring_tokens: Select the headers from the request that need to be included in the StringToSign .
function: def headers_to_sign(self, http_request):
          """
          Select the headers from the request that need to be included
          in the StringToSign.
          """
          headers_to_sign = {'Host': self.host}
          for name, value in http_request.headers.items():
              lname = name.lower()
              if lname.startswith('x-amz'):
                  headers_to_sign[name] = value
          return headers_to_sign
function_tokens: def headers_to_sign ( self , http_request ) : headers_to_sign = { 'Host' : self . host } for name , value in http_request . headers . items ( ) : lname = name . lower ( ) if lname . startswith ( 'x-amz' ) : headers_to_sign [ name ] = value return headers_to_sign