/**
 * Graphology isGraph
 * ===================
 *
 * Very simple function aiming at ensuring the given variable is a
 * graphology instance.
 */

/**
 * Checking the value is a graphology instance.
 *
 * @param  {any}     value - Target value.
 * @return {boolean}
 */
module.exports = function isGraph(value) {
  return (
    value !== null &&
    typeof value === 'object' &&
    typeof value.addUndirectedEdgeWithKey === 'function' &&
    typeof value.dropNode === 'function' &&
    typeof value.multi === 'boolean'
  );
};