code: function Pragma(n) {
      if (n.type === SEMICOLON) {
          var e = n.expression;
          if (e.type === STRING && e.value === "use strict") {
              n.pragma = "strict";
              return true;
          }
      }
      return false;
  }
docs: /*
  Pragma :: (expression statement node) -> boolean
  
  Checks whether a node is a pragma and annotates it.