<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_call_exprs(self, line):
 """Gets the argument expressions from the source of a function call."""

        line = line.lstrip()
        try:
            tree = self.ast.parse(line)
        except SyntaxError:
            return None
        for node in self.ast.walk(tree):
            if isinstance(node, self.ast.Call):
                offsets = []
                for arg in node.args:
                    # In Python 3.4 the col_offset is calculated wrong. See
                    # https://bugs.python.org/issue21295
                    if isinstance(arg, self.ast.Attribute) and (
                            (3, 4, 0) <= self.sys.version_info <= (3, 4, 3)):
                        offsets.append(arg.col_offset - len(arg.value.id) - 1)
                    else:
                        offsets.append(arg.col_offset)
                if node.keywords:
                    line = line[:node.keywords[0].value.col_offset]
                    line = self.re.sub(r'\w+\s*=\s*$', '', line)
                else:
                    line = self.re.sub(r'\s*\)\s*$', '', line)
                offsets.append(len(line))
                args = []
                for i in range(len(node.args)):
                    args.append(line[offsets[i]:offsets[i + 1]].rstrip(', '))
                return args