================================
Minimal
================================
if true then
end if;

L2:
if true then
end if;

L3:
if true then
end if L3;
---

(design_file
  (if_statement
    (if
      (conditional_expression
        (simple_name))))
  (if_statement
    (label
      (identifier))
    (if
      (conditional_expression
        (simple_name))))
  (if_statement
    (label
      (identifier))
    (if
      (conditional_expression
        (simple_name)))
    at_end: (simple_name)))

================================
Elsif
================================
if true then
elsif true then
end if;
---

(design_file
  (if_statement
    (if
      (conditional_expression
        (simple_name)))
    (elsif
      (conditional_expression
        (simple_name)))))

================================
Else
================================
if true then
elsif true then
else
end if;
---

(design_file
  (if_statement
    (if
      (conditional_expression
        (simple_name)))
    (elsif
      (conditional_expression
        (simple_name)))
    (else)))

================================
Sequence os statements
================================
if true then
    null;
elsif true then
    null;
    null;
else
    null;
    null;
    null;
end if;
---

(design_file
  (if_statement
    (if
      (conditional_expression
        (simple_name))
      (sequence_of_statements
        (null_statement)))
    (elsif
      (conditional_expression
        (simple_name))
      (sequence_of_statements
        (null_statement)
        (null_statement)))
    (else
      (sequence_of_statements
        (null_statement)
        (null_statement)
        (null_statement)))))
