parameters: (self, real_dns_lookup)
docstring: Initialize RealHttpFetch.
  
      Args:
        real_dns_lookup: a function that resolves a host to an IP. RealHttpFetch
          will resolve host name to the IP before making fetching request if this
          is not None.
docstring_summary: Initialize RealHttpFetch.
docstring_tokens: Initialize RealHttpFetch .
function: def __init__(self, real_dns_lookup):
      """Initialize RealHttpFetch.
  
      Args:
        real_dns_lookup: a function that resolves a host to an IP. RealHttpFetch
          will resolve host name to the IP before making fetching request if this
          is not None.
      """
      self._real_dns_lookup = real_dns_lookup
function_tokens: def __init__ ( self , real_dns_lookup ) : self . _real_dns_lookup = real_dns_lookup