IPv6 Shortener

An IPv6-Address is the next-generation network address for electronic devices. Compared to an IPv4 address, it is made up of 8 blocks that are 4 hexadecimal digits long, split by colons. An example of an IPv6 address is [[2001:0000:3c4d:0015:0000:0000:0db8:1a2b]] To avoid needing to write so many digits, you can short an IPv6 address very easily by removing unneeded zeros. The goal of this puzzle is to compress the IPv6 address, that it gets shortened. The shortened version would look like this: [[2001:0:3c4d:15::db8:1a2b]] You can see that the leading zeros of all the blocks were removed, and a double colon replaced the longest chains of blocks that contained zeros only. <<Notes:>> The double colon may only be used once in the whole address at the longest streak of zero blocks, and only if there are two or more zero blocks next to each other. The rest of the single blocks that contain zeros only must be represented as only one zero in the whole block, no matter if they are next to each other.