lib/insert-mode.js
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; 
  }
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; 
  }
returns true if we are to write to terminal