code: public void setLetterSpacing (float letterSpacing){
          if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
  		    mInputView.setLetterSpacing(letterSpacing);
  	}
docs: Sets text letter-spacing.  The value is in 'EM' units.  Typical values
  for slight expansion will be around 0.05.  Negative values tighten text.
  
  @see #getLetterSpacing()
  @see android.graphics.Paint#getLetterSpacing
  
  @attr ref android.R.styleable#TextView_letterSpacing