code: function pathAll(propertyPath) {
    return propertyPath.split('.').reduce((a, v, i) => {
      a[i] = i === 0 ? v : a[i-1] + '.' + v;
      return a;
    }, []);
  }
docs: For a single dot-delimited path like 'when.harry.met.sally', returns:
  
  ['when', 'when.harry', 'when.harry.met', 'when.harry.met.sally']
  
  @param propertyPath A full dot-delimited path.
  @returns {*}