code: function validIncrement( x ) {
  	var N = units.length,
  		sign = false,
  		parts,
  		len,
  		unit,
  		val,
  		flg,
  		i;
  
  	if ( typeof x === 'number' ) {
  		if ( x !== x ) {
  			throw new TypeError( 'incrdatespace()::invalid value. Increment must be a valid number.' );
  		}
  		return x;
  	}
  	if ( typeof x !== 'string' ) {
  		throw new TypeError( 'incrdatespace()::invalid value. Increment must be either a string or number.' );
  	}
  	// Convert the formatted string to milliseconds...
  	if ( x[ 0 ] === '-' ) {
  		sign = true;
  		x = x.substr( 1 );
  	}
  	parts = x.split( '.' );
  	len = parts.length;
  	x = 0;
  	while ( len ) {
  		flg = false;
  		val = parts.pop();
  		if ( !fmt.test( val ) ) {
  			throw new Error( 'incrdatespace()::invalid value. Scalar unit pair must have the following format: `ms`, `5ms`, `5days`, etc.' );
  		}
  		for ( i = 0; i < N; i++ ) {
  			unit = units[ i ];
  			if ( reUnits[ unit ].test( val ) ) {
  				flg = true;
  				val = parseInt( val, 10 );
  				if ( val !== val ) {
  					// No scalar...
  					val = 1;
  				}
  				x += val * convert[ unit ];
  				break;
  			}
  		}
  		if ( !flg ) {
  			throw new Error( 'incrdatespace()::invalid value. Unrecognized unit: `' + val + '`.' );
  		}
  		len = parts.length;
  	}
  	if ( sign ) {
  		return -x;
  	}
  	return x;
  }
docs: end FUNCTION validDate() 
  FUNCTION: validIncrement( x )
  Validates an increment.
  
  @private
  @param {String|Number} x - increment to be validated
  @returns {Number} increment in milliseconds