~> perl -Mstrict -Mwarnings -le 'my %foo = ( abc1 => "hello" ); print "ok"'
ok
~> perl -Mstrict -Mwarnings -le 'my %foo = ( 1abc => "hello" ); print "ok"'
syntax error at -e line 1, near "1abc"
Execution of -e aborted due to compilation errors.
~>