use Data::Dumper; To dump:

open DUMP, ">$dump_path" or die "Couldn't open file to dump: $!";
print DUMP Data::Dumper->Dump([\%coords], ['coords']);
close DUMP;    # close the city dump
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To load:

open LOAD, "<$dump_path" or die "Couldn't open file to load: $!";
local $/;
$/ = undef;
my $struct = <LOAD>;
close LOAD;
eval { $struct };
# then access %coords as usual
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--
my one true love