title: Makefile: return first two characters of a string
body: <p>Given a string in a Makefile, is it possible to extract the first two characters of an unknown string using Makefile syntax (without using shell calls)?</p>
  
  <p>for instance,</p>
  
  <pre><code>VAR := UnKnown
  VAR_TERSE = $(call get_first_two_chars, $(VAR))
  
  define get_first_two_char
  ...
  endef
  </code></pre>