text: type Note = {
    letter: string,
    acc: string,
    pc: string,
    step: number,
    alt: number,
    chroma: number,
    oct: ?number,
    midi: ?number,
    freq: ?number,
  };
  
  declare module 'note-parser' {
    declare function regex(): RegExp;
    declare function parse(note: string, isTonic: boolean, tuning: number): Note;
    declare function build(obj: Object): string;
    declare function midi(note: string | number): number;
    declare function freq(note: string, tuning: ?string): number;
  }
  