Function add_patch 

pub fn add_patch(
    tree: &dyn PyWorkingTree,
    patches_directory: &Path,
    name: &str,
    contents: &[u8],
    header: Option<PatchHeader>,
) -> Result<(Vec<PathBuf>, String), String>

Add a new patch.

Arguments

• tree - Tree to edit
• patches_directory - Name of patches directory
• name - Patch name without suffix
• contents - Diff
• header - RFC822 to read

Returns: Name of the patch that was written (including suffix)