code: function tryMatchSequence(key) {
      seq.keys.push(key.name);
      
      // remember when last key was entered so we can decide if it counts as sequence or not
      var m = vim.map.matchInsert(seq.keys) 
        // assume we'll match no complete sequence and therefore will want to print keyed char
        , passThru = true;
  
      if (!m) {
        // in case we buffered some keys hoping for a complete sequence, loose hope now
        self.clearSequence();
      } else if (m === true) {
        // we hope for a future match
      } else if (matchSequence(m)) { 
        // we matched our sequence and therefore will not print the char
        passThru = false;
      }
      
      if (passThru) seq.last = new Date();
      return passThru; 
    }
docs: returns true if we are to write to terminal