error: passing a unit value to a function
   --> rdftk_io/src/turtle/writer.rs:662:9
    |
662 | /         Ok(if let Some(literal) = literal.as_literal() {
663 | |             match literal.data_type() {
664 | |                 Some(DataType::Iri) => {
665 | |                     let iri = Iri::parse(literal.lexical_form())?;
...   |
694 | |             panic!("ERROR: this is not a literal: {:?}", literal)
695 | |         })
    | |__________^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unit_arg
    = note: `-D clippy::unit-arg` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(clippy::unit_arg)]`
help: move the expression in front of the call and replace it with the unit literal `()`
    |
662 ~         if let Some(literal) = literal.as_literal() {
663 +             match literal.data_type() {
664 +                 Some(DataType::Iri) => {
665 +                     let iri = Iri::parse(literal.lexical_form())?;
666 +                     self.write_iri(w, graph, &iri)?
667 +                 }
668 +                 Some(DataType::Boolean)
669 +                 | Some(DataType::Long)
670 +                 | Some(DataType::Int)
671 +                 | Some(DataType::Short)
672 +                 | Some(DataType::Byte)
673 +                 | Some(DataType::UnsignedLong)
674 +                 | Some(DataType::UnsignedInt)
675 +                 | Some(DataType::UnsignedShort)
676 +                 | Some(DataType::UnsignedByte)
677 +                 | Some(DataType::Float)
678 +                 | Some(DataType::Double)
679 +                 | Some(DataType::Decimal) => write!(w, "{}", literal.lexical_form())?,
680 +                 _ => {
681 +                     write!(w, "{:?}", literal.lexical_form())?;
682 +                     match (literal.data_type(), literal.language()) {
683 +                         (Some(data_type), None) => {
684 +                             write!(w, "{DATATYPE_PREFIX}")?;
685 +                             let iri = data_type.as_iri();
686 +                             self.write_iri(w, graph, iri)?;
687 +                         }
688 +                         (None, Some(language)) => write!(w, "{LANGUAGE_PREFIX}{}", language)?,
689 +                         _ => (),
690 +                     }
691 +                 }
692 +             }
693 +         } else {
694 +             panic!("ERROR: this is not a literal: {:?}", literal)
695 +         };
696 +         Ok(())
    |

error: constant `COLLECTION_END` is never used
   --> rdftk_io/src/turtle/writer.rs:122:7
    |
122 | const COLLECTION_END: &str = ")";
    |       ^^^^^^^^^^^^^^

error: constant `COLLECTION_START` is never used
   --> rdftk_io/src/turtle/writer.rs:121:7
    |
121 | const COLLECTION_START: &str = "(";
    |       ^^^^^^^^^^^^^^^^
    |
    = note: `-D dead-code` implied by `-D warnings`
    = help: to override `-D warnings` add `#[allow(dead_code)]`