%hash = (key_is_unquoted => 42);         # unquoted key name
print "$hash{key_is_unquoted}\n";        # unquoted key, prints: 42
print "$hash{'key_is_unquoted'}\n";      # quoted key, prints: 42

%hash2 = ('key_is_quoted' => 255);       # quoted key name
print "$hash2{'key_is_quoted}'\n";       # quoted key, prints: 255
print "$hash2{key_is_quoted}\n";         # unquoted key, prints: 255

%hash3 = (key => value);                 # unquoted key and value
print "$hash3{key}\n";                   # unquoted key, prints: value
print "$hash3{'key'}\n";                 # quoted key, prints: value