code: @Override
      public FieldText WHEN(final int depth, final FieldText fieldText) {
          return new FieldTextBuilder(this).WHEN(depth, fieldText);
      }
docs: Appends another fieldtext expression onto the end of this expression using the WHEN<i>n</i> operator. The
  returned {@link FieldText} object is equivalent to:
  
  <pre>(this) WHEN<i>n</i> (fieldText)</pre>
  
  @param depth The <i>n</i> in WHEN<i>n</i>
  @param fieldText A fieldtext expression or specifier.
  @return The combined expression.