function placeHoldersCount (b64) {
var len = b64.length
if (len % 4 > 0) {
  throw new Error('Invalid string. Length must be a multiple of 4')
}

// the number of equal signs (place holders)
// if there are two placeholders, than the two characters before it
// represent one byte
// if there is only one, then the three characters before it represent 2 bytes
// this is just a cheap hack to not do indexOf twice
return b64[len - 2] === '=' ? 2 : b64[len - 1] === '=' ? 1 : 0
}
Converts a JavaScript value to a YAML string.

@param   {*} value - The value to convert to YAML
@param   {function|array} replacer - Not currently supported. Provided for consistency with {@link JSON.stringify}
@param   {string|number} space - The number of spaces to use for indentation, or a string containing the number of spaces.
@returns {string}