def inject_interface_into_readme(interface_file: str, readme_file: str=
    'README.md') ->None:
    """
    Add content of help.txt into README.md
    Content of help.txt will be placed into the first code block (```) of README.md.
    If no code block is found, a new one will be added to the beginning of README.md.
    """
    readme_str: str = open(readme_file, 'r').read()
    interface_str = open(interface_file, 'r').read()
    help_str: str = f'```\n{interface_str}\n```'
    start: int = readme_str.find('```') + 3
    end: int = readme_str.find('```', start)
    if '```' in readme_str:
        mod_str: str = readme_str[0:start - 3] + help_str + readme_str[end + 3:
            ]
    else:
        mod_str = help_str + readme_str
    with open('README.md', 'w') as modified_readme:
        modified_readme.write(mod_str)
