def physical_cpus():
if platform.system() == '<STR_LIT>':<EOL><INDENT>ncores = subprocess.check_output(<EOL>['<STR_LIT>', '<STR_LIT>', '<STR_LIT>'], shell=False<EOL>)<EOL>return int(ncores.strip())<EOL><DEDENT>sockets = set()<EOL>with open('<STR_LIT>') as istr:<EOL><INDENT>for line in istr:<EOL><INDENT>if line.startswith('<STR_LIT>'):<EOL><INDENT>sockets.add(line.split('<STR_LIT::>')[-<NUM_LIT:1>].strip())<EOL><DEDENT><DEDENT><DEDENT>return len(sockets)<EOL>
Get cpus identifiers, for instance set(["0", "1", "2", "3"])

    :return Number of physical CPUs available
    :rtype: int