def extract_variables(self, content: str) -> list[str]:
        """Extract variables from the content.

        Variables are in the format ${variable_name}.
        """
        pattern = r'\$\{([a-zA-Z_][a-zA-Z0-9_]*)\}'
        matches = re.findall(pattern, content)
        return matches
Extract variables from the content.

        Variables are in the format ${variable_name}.
        
openhands/microagent/microagent.py