<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def set_connection_string_by_user_input(self):
 """Prompts the user to input a connection string"""

        user_connection = input(
            bcolors.WARNING + "\nFor any reason connection to " + bcolors.ENDC +
            bcolors.FAIL + "{}".format(self.connection) + bcolors.ENDC +
            bcolors.WARNING + " is not possible.\n\n" + bcolors.ENDC +
            "For more information about SQLAlchemy connection strings go to:\n" +
            "http://docs.sqlalchemy.org/en/latest/core/engines.html\n\n"
            "Please insert a valid connection string:\n" +
            bcolors.UNDERLINE + "Examples:\n\n" + bcolors.ENDC +
            "MySQL (recommended):\n" +
            bcolors.OKGREEN + "\tmysql+pymysql://user:passwd@localhost/database?charset=utf8\n" + bcolors.ENDC +
            "PostgreSQL:\n" +
            bcolors.OKGREEN + "\tpostgresql://scott:tiger@localhost/mydatabase\n" + bcolors.ENDC +
            "MsSQL (pyodbc have to be installed):\n" +
            bcolors.OKGREEN + "\tmssql+pyodbc://user:passwd@database\n" + bcolors.ENDC +
            "SQLite (always works):\n" +
            " - Linux:\n" +
            bcolors.OKGREEN + "\tsqlite:////absolute/path/to/database.db\n" + bcolors.ENDC +
            " - Windows:\n" +
            bcolors.OKGREEN + "\tsqlite:///C:\\path\\to\\database.db\n" + bcolors.ENDC +
            "Oracle:\n" +
            bcolors.OKGREEN + "\toracle://user:passwd@127.0.0.1:1521/database\n\n" + bcolors.ENDC +
            "[RETURN] for standard connection {}:\n".format(defaults.sqlalchemy_connection_string_default)
        )
        if not (user_connection or user_connection.strip()):
            user_connection = defaults.sqlalchemy_connection_string_default
        set_connection(user_connection.strip())