%h = (a => 1, b => 2, "*" => 3, 4 => '4a', ab => 42);
@a = (1,2,3,4);
$_ = 'aaaa';

print qq|@h{s+a+a+g}\n|;         # 4a:  warnings  
print qq|@h{s/a/a/g}\n|;         # 4a: no warnings

print qq|@h{qw'a b'}\n|;         # 1 2: warnings
print qq|@h{qw"a b"}\n|;         # 1 2: warnings
print qq|@h{qw+a b+}\n|;         # 1 2: warnings

print qq|@h{qw(a b)}\n|;         # 1 2: no warnings
print qq|@h{qw/a b/}\n|;         # 1 2: no warnings
print qq|@h{qw'b *'}\n|;         # 2 3: no warnings

print qq|@h{2 + 2}\n|;           # 4a:  warnings
print qq|@h{3 + 5 - 4}\n|;       # 4a:  warnings
print qq|@h{2 * 2}\n|;           # 4a: no warnings
print qq|@h{(3 + 5) - 4}\n|;     # 4a: no warnings

print qq|@h{'a'}\n|;             # 1:  warnings
print qq|@h{'*'}\n|;             # 3:  no warnings
print qq|@h{qq*a*}\n|;           # 1:  no warnings
print qq|@h{'a'.'b'}\n|;         # 42: no warnings

print qq|@h{$a[3]}\n|;           # 4a: no warnings
print qq|@h{scalar @a}\n|;       # 4a: no warnings