According document of 'What’s New In Python 3.7', 'async' are reserved keywords now.

Code in line 105 of 'odoo/addons/base/ir/ir_qweb/assetsbundle.py' 
`def to_html(self, sep=None, css=True, js=True, debug=False, async=False, url_for=(lambda url: url)):`
will throw SyntaxError out if we launch odoo with this update python.
odoo/tools/safe_eval.py
'bool': bool,
    'int': int,
    'float': float,
    'enumerate': enumerate,
    'dict': dict,
    'list': list,
    'tuple': tuple,
    'map': map,
    'abs': abs,
    'min': min,
    'max': max,
    'sum': sum,
    'reduce': functools.reduce,
    'filter': filter,
    'round': round,
    'len': len,
    'repr': repr,
    'set': set,
    'all': all,
    'any': any,
    'ord': ord,
    'chr': chr,
    'divmod': divmod,
    'isinstance': isinstance,
    'range': range,
    'xrange': range,
    'zip': zip,
    'Exception': Exception,
}
def safe_eval(expr, globals_dict=None, locals_dict=None, mode="eval", nocopy=False, locals_builtins=False):