code: function getUnit() {
    const type = NodeType.IdentType;
    const token = tokens[pos];
    const line = token.ln;
    const column = token.col;
    const content = token.value;
  
    pos++;
  
    return newNode(type, content, line, column);
  }
docs: Get unit node of type ident
  @return {Node} An ident node containing the unit value