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/// @startDocuBlock JSF_post_api_index_geo
/// @brief creates a geo index
///
/// @RESTHEADER{POST /_api/index#geo, Create geo-spatial index}
///
/// @RESTQUERYPARAMETERS
///
/// @RESTQUERYPARAM{collection,string,required}
/// The collection name.
///
/// 
/// @RESTBODYPARAM{type,string,required,string}
/// must be equal to *"geo"*.
///
/// @RESTBODYPARAM{fields,array,required,string}
/// An array with one or two attribute paths.
///
/// If it is an array with one attribute path *location*, then a geo-spatial
/// index on all documents is created using *location* as path to the
/// coordinates. The value of the attribute must be an array with at least two
/// double values. The array must contain the latitude (first value) and the
/// longitude (second value). All documents, which do not have the attribute
/// path or with value that are not suitable, are ignored.
///
/// If it is an array with two attribute paths *latitude* and *longitude*,
/// then a geo-spatial index on all documents is created using *latitude*
/// and *longitude* as paths the latitude and the longitude. The value of
/// the attribute *latitude* and of the attribute *longitude* must a
/// double. All documents, which do not have the attribute paths or which
/// values are not suitable, are ignored.
///
/// @RESTBODYPARAM{geoJson,string,required,string}
/// If a geo-spatial index on a *location* is constructed
/// and *geoJson* is *true*, then the order within the array is longitude
/// followed by latitude. This corresponds to the format described in
/// http://geojson.org/geojson-spec.html#positions
///
/// @RESTDESCRIPTION
/// **NOTE** Swagger examples won't work due to the anchor.
///
///
/// Creates a geo-spatial index in the collection *collection-name*, if
/// it does not already exist. Expects an object containing the index details.
///
/// Geo indexes are always sparse, meaning that documents that do not contain
/// the index attributes or have non-numeric values in the index attributes
/// will not be indexed.
///
/// @RESTRETURNCODES
///
/// @RESTRETURNCODE{200}
/// If the index already exists, then a *HTTP 200* is returned.
///
/// @RESTRETURNCODE{201}
/// If the index does not already exist and could be created, then a *HTTP 201*
/// is returned.
///
/// @RESTRETURNCODE{404}
/// If the *collection-name* is unknown, then a *HTTP 404* is returned.
///
/// @EXAMPLES
///
/// Creating a geo index with a location attribute
///
/// @EXAMPLE_ARANGOSH_RUN{RestIndexCreateGeoLocation}
///     var cn = "products";
///     db._drop(cn);
///     db._create(cn);
///
///     var url = "/_api/index?collection=" + cn;
///     var body = { 
///       type: "geo", 
///       fields : [ "b" ] 
///     };
///
///     var response = logCurlRequest('POST', url, body);
///
///     assert(response.code === 201);
///
///     logJsonResponse(response);
///   ~ db._drop(cn);
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// Creating a geo index with latitude and longitude attributes
///
/// @EXAMPLE_ARANGOSH_RUN{RestIndexCreateGeoLatitudeLongitude}
///     var cn = "products";
///     db._drop(cn);
///     db._create(cn);
///
///     var url = "/_api/index?collection=" + cn;
///     var body = { 
///       type: "geo", 
///       fields: [ "e", "f" ] 
///     };
///
///     var response = logCurlRequest('POST', url, body);
///
///     assert(response.code === 201);
///
///     logJsonResponse(response);
///   ~ db._drop(cn);
/// @END_EXAMPLE_ARANGOSH_RUN
/// @endDocuBlock
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