Create a graph drawing a line between each pair of (src_lat, src_lon) and (dest_lat, dest_lon)

    :param data: data access object
    :param src_lat: field name of source latitude
    :param src_lon: field name of source longitude
    :param dest_lat: field name of destination latitude
    :param dest_lon: field name of destination longitude
    :param linewidth: line width
    :param alpha: color alpha
    :param color: color or colormap

def graph(data, src_lat, src_lon, dest_lat, dest_lon, linewidth=1, alpha=220, color='hot'):
    """Create a graph drawing a line between each pair of (src_lat, src_lon) and (dest_lat, dest_lon)

    :param data: data access object
    :param src_lat: field name of source latitude
    :param src_lon: field name of source longitude
    :param dest_lat: field name of destination latitude
    :param dest_lon: field name of destination longitude
    :param linewidth: line width
    :param alpha: color alpha
    :param color: color or colormap
    """
    from geoplotlib.layers import GraphLayer
    _global_config.layers.append(GraphLayer(data, src_lat, src_lon, dest_lat, dest_lon, linewidth, alpha, color))