Parse a Rust source file into a syn::File and print out a debug representation
of the syntax tree.
Use the following command from this directory to test this program by running it on its own source code:
cargo run -- src/main.rs
The output will begin with:
File {
shebang: None,
attrs: [
Attribute {
pound_token: Pound,
style: Inner(
Bang
),
bracket_token: Bracket,
path: Path {
leading_colon: None,
segments: [
...
}