nested elseif woes

First thanks to Tom Lane who helped me promptly.

Now let's come to the problem:

create or replace function testa( )
returns char(32) as
'
begin
if 1=2 then
if 1=2 then
select 1;
elseif 1=3 then
select 2;
elseif 1=4 then
if 1=5 then
select 3;
else
select 4;
end if;
end if;
end if;
return md5(''aaaa'');
end;
' language plpgsql;

test1=# select * from testa();
ERROR: syntax error at or near "if"
CONTEXT: compile of PL/pgSQL function "testa" near line 14

I made several test functions with similar structure with no
improvements.
I can't even figure a pattern. I get errors on if, else, and elseif.
Till now the culprit seems to be elseif. Whenever I write test
functions without elseif I get no errors.
Did I misinterpreted the docs (37.7.2.4)?

I really can't see the problem.

I'm running 7.4.2-1 on Debian Sarge.

To be less annoying to the list, could anyone point me to somewhere
where I could look at functions written by others.
Any good project with enough complicated functions to be useful to
learn.

thx