Function get_string 

pub unsafe extern "C" fn get_string(
    context: *mut c_context,
    value: *const value,
    callback: get_string_callback,
    user_data: *mut c_void,
) -> err

@brief Get the raw string @ingroup value_extract

This may contain placeholders.

@param[out] context Optional, stores error information @param[in] value Nix value to inspect @param[in] callback Called with the string value. @param[in] user_data optional, arbitrary data, passed to the callback when it’s called. @return error code, NIX_OK on success.