code: function blockWrap(contract, expression) {
    return contract.slice(0, expression.start) + '{' + contract.slice(expression.start, expression.end) + '}' + contract.slice(expression.end);
  }
docs: Splices enclosing brackets into `contract` around `expression`;
  @param  {String} contract solidity source
  @param  {Object} node     AST node to bracket
  @return {String}          contract