Returns a dictionary of the Weld supported unary ops, with values being their Weld symbol.

def get_supported_unary_ops():
    '''
    Returns a dictionary of the Weld supported unary ops, with values being their Weld symbol.
    '''
    unary_ops = {}
    unary_ops[np.exp.__name__] = 'exp'
    unary_ops[np.log.__name__] = 'log'
    unary_ops[np.sqrt.__name__] = 'sqrt'
    return unary_ops