@react-bootstrap/react-popper/lib/cjs/utils.js.flow

React wrapper around Popper.js

// @flow

/**
 * Takes an argument and if it's an array, returns the first item in the array,
 * otherwise returns the argument. Used for Preact compatibility.
 */
export const unwrapArray = (arg: *): * => (Array.isArray(arg) ? arg[0] : arg);

/**
 * Takes a maybe-undefined function and arbitrary args and invokes the function
 * only if it is defined.
 */
export const safeInvoke = (fn: ?Function, ...args: *) => {
  if (typeof fn === "function") {
    return fn(...args);
  }
}