Not able to use bitcoin/bitcoin.hpp

Not able to use bitcoin/bitcoin.hpp

the libbitcoin library seems to have been installed just fine. but the following code can't seem to include bitcoin/bitcoin.hpp

#include<bitcoin/bitcoin.hpp>
#include<iostream>
using namespace bc;
int main() {
    block_type blk = genesis_block();
    std::cout<<encode_hex(hash_block_header(blk.header))<<std::endl;
    return 0;
}

Error:

g++ -o test test.cpp $(pkg-config --cflags --libs libbitcoin)
test.cpp: In function ‘int main()’:
test.cpp:5:5: error: ‘block_type’ was not declared in this scope
     block_type blk = genesis_block();
     ^~~~~~~~~~
test.cpp:5:5: note: suggested alternative: ‘clock_t’
     block_type blk = genesis_block();
     ^~~~~~~~~~
     clock_t
test.cpp:6:45: error: ‘blk’ was not declared in this scope
     std::cout<<encode_hex(hash_block_header(blk.header))<<std::endl;
                                             ^~~
test.cpp:6:45: note: suggested alternative: ‘brk’
     std::cout<<encode_hex(hash_block_header(blk.header))<<std::endl;
                                             ^~~
                                             brk
test.cpp:6:27: error: ‘hash_block_header’ was not declared in this scope
     std::cout<<encode_hex(hash_block_header(blk.header))<<std::endl;
                           ^~~~~~~~~~~~~~~~~
test.cpp:6:16: error: ‘encode_hex’ was not declared in this scope
     std::cout<<encode_hex(hash_block_header(blk.header))<<std::endl;
                ^~~~~~~~~~

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