parameters: (self, fields, verbose=True)
return_statement: return self._ext_bases[join_base]
docstring: Get joined base from the fields who have join.
  
          :param fields:  the iterable of fields
          :param verbose: boolean, toggle verbosity
          :returns:       a GeoBase object or ``None`` if fields are not joined
  
          >>> geo_o.getJoinBase('iata_code')
          Fields "('iata_code',)" do not have join, cannot retrieve external base.
          >>> geo_o.getJoinBase('country_code') # doctest: +SKIP
          <GeoBases.GeoBaseModule.GeoBase object at 0x...>
docstring_summary: Get joined base from the fields who have join.
docstring_tokens: Get joined base from the fields who have join .
function: def getJoinBase(self, fields, verbose=True):
          """Get joined base from the fields who have join.
  
          :param fields:  the iterable of fields
          :param verbose: boolean, toggle verbosity
          :returns:       a GeoBase object or ``None`` if fields are not joined
  
          >>> geo_o.getJoinBase('iata_code')
          Fields "('iata_code',)" do not have join, cannot retrieve external base.
          >>> geo_o.getJoinBase('country_code') # doctest: +SKIP
          <GeoBases.GeoBaseModule.GeoBase object at 0x...>
          """
          fields = tuplify(fields)
  
          if not self.hasJoin(fields):
              if verbose:
                  print 'Fields "%s" do not have join, cannot retrieve external base.' % str(fields)
              return
  
          # This is the data type of the joined base
          join_base = self._join[fields][0]
  
          return self._ext_bases[join_base]
function_tokens: def getJoinBase ( self , fields , verbose = True ) : fields = tuplify ( fields ) if not self . hasJoin ( fields ) : if verbose : print 'Fields "%s" do not have join, cannot retrieve external base.' % str ( fields ) return # This is the data type of the joined base join_base = self . _join [ fields ] [ 0 ] return self . _ext_bases [ join_base ]