human
Solve the following python programming problem given the following code:
def _system_tree_dict(system, size_1 = True, expand_level = 9999) : 
    '
    Returns a dict representation of the system hierarchy with
    the given System as root.
    ' 
    def _tree_dict(ss, level) : 
        dct = { 
            'name' : ss.name, 
} 
        children = [_tree_dict (s, (level + 1)) for s in ss.subsystems ()] 
        if isinstance (ss, Component) : 
            for (vname, meta) in ss.unknowns.items () : 
                size = (meta ['size'] if (meta ['size'] and (not size_1)) else 1) 
                children.append ({ 
                    'name' : vname, 
                    'size' : size, 
}) 
for (vname, meta) in ss.params.items () : 
                size = (meta ['size'] if (meta ['size'] and (not size_1)) else 1) 
                children.append ({ 
                    'name' : vname, 
                    'size' : size, 
}) 
if (level > expand_level) : 
            dct ['_children'] = children 
            dct ['children'] = None 
else : 
            dct ['children'] = children 
            dct ['_children'] = None 
return dct 
tree = _tree_dict (expand_level, 1) 
    if (not tree ['name']) : 
        tree ['name'] = 'root' 
return tree 

    
    

    Fix the buggy line: tree = _tree_dict (expand_level, 1)
assistant
#Here is Python code to fix the buggy line: tree = _tree_dict (expand_level, 1)
.

tree = _tree_dict (system, 1)