returns a clean MOL block representation of molecule

Example request

{
  "struct": "\n  Ketcher  7292215 12D 1   1.00000     0.00000     0\n\n  7  7  0     0  0            999 V2000\n   17.3000   -4.3000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0\n   18.1660   -4.8000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0\n   18.1660   -5.8000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0\n   17.3000   -6.3000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0\n   16.4340   -5.8000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0\n   16.4340   -4.8000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0\n   17.3000   -3.3000    0.0000 C   0  0  0  0  0  0  0  0  0  0  0  0\n  1  2  1  0     0  0\n  2  3  2  0     0  0\n  3  4  1  0     0  0\n  4  5  2  0     0  0\n  5  6  1  0     0  0\n  6  1  2  0     0  0\n  1  7  1  0     0  0\nM  END\n"
}