code: function normalizeProperties(props) {
    const output = {};
    for (let p in props) {
      const o = props[p];
      output[p] = (typeof o === 'function') ? {type: o} : o;
    }
    return output;
  }
docs: Creates a copy of `props` with each property normalized such that
  upgraded it is an object with at least a type property { type: Type}.
  
  @param {Object} props Properties to normalize
  @return {Object} Copy of input `props` with normalized properties that
  are in the form {type: Type}
  @private