Expr tree

This worked in python 2.7.5, before I would get error:

Traceback (most recent call last):
  File "ex.py", line 34, in <module>
    val = p.solve(solver=cp.CVXOPT, verbose=True, solver_specific_opts=opts_cvxopt)
  File "/Library/Python/2.7/site-packages/cvxpy-0.1-py2.7.egg/cvxpy/problems/problem.py", line 264, in solve
    return self._solve(*args, **kwargs)
  File "/Library/Python/2.7/site-packages/cvxpy-0.1-py2.7.egg/cvxpy/problems/problem.py", line 358, in _solve
    verbose, solver_specific_opts)
  File "/Library/Python/2.7/site-packages/cvxpy-0.1-py2.7.egg/cvxpy/problems/problem.py", line 549, in _cvxopt_solve
    for key, value in opts:
ValueError: too many values to unpack