Methods to calculate U.S.A. zip code distances and city proximities.

The following operations are supported. For a formal definition, please review the Service Description.

• GetLocationsNearZipcode
  Returns a set of locations within the radius of the given zipcode.
• GetZipDistance
  Returns the distance in miles between two zipcodes.
• GetZipsFromCityName
  Returns a set of zipcodes for the SOUNDEX of the given city.