function substring(subject, start, end) {
    return coerceToString(subject).substring(start, end);
  }
Extracts from `subject` a string from `start` position up to `end` position. The character at `end` position is not
included.

@function substring
@static
@since 1.0.0
@memberOf Chop
@param  {string} [subject='']         The string to extract from.
@param  {number} start                The position to start extraction.
@param  {number} [end=subject.length] The position to end extraction.
@return {string}                      Returns the extracted string.
@note Uses native `String.prototype.substring()`
@example
v.substring('beach', 1);
// => 'each'

v.substring('ocean', 1, 3);
// => 'ea'