function accumulator( input ) {
		if ( arguments.length === 0 ) {
			return acc();
		}
		return acc( lloc( input ) );
	}
If provided a value, the accumulator function returns an updated logical lines of code (LLOC) summary. If not provided a value, the accumulator function returns the current LLOC summary.

@private
@param {(string|Buffer)} [input] - input program
@throws {TypeError} must provide either a string or Buffer
@returns {Object} LLOC summary

@example
var lloc = accumulator();
// returns {}

lloc = accumulator( '"use strict";\n\nvar y = 5;\n' );
// returns {...}

lloc = accumulator( '"use strict";\n\nmodule.exports = "beep";\n' );
// returns {...}

lloc = accumulator();
// returns {...}