env: variable()

This is a convenient factory function for Variable objects.

variable() is defined in env and can be accessed like that:

import {variable} from 'deep6/env.js';

The current implementation:

const variable = name => new Variable(name);

Example of use:

import {variable} from 'deep6/env.js';

const x = variable(),                  // anonymous
  y = variable('pilot'),               // named
  z = variable(Symbol.for('trend')),   // uses a global symbol

  a = variable('pilot'),               // the same as "y" above
  b = variable(Symbol.for('trend')),   // the same as "z" above
  c = variable(Symbol('rocket'));      // uses a named symbol