 ```python
import pymapdl

with pymapdl.open_mapdl(debug=True) as mapdl:
    mapdl.prep7()

    # Create first block and mesh it with tetrahedral elements
    mapdl.block("create", "box", 0, 1, 0, 1, 0, 1)
    mapdl.block("mesh", "quality", "tet")

    # Create second volume block above the existing one and mesh it with quadratic hexahedral elements
    mapdl.block("create", "box", 0.1, 0.9, 0.1, 0.9, 1.1, 1.5)
    mapdl.block("mesh", "quality", "hex", "brick20")

    # Generate contact elements for general contact
    mapdl.contact("genel", "all", "all", "s", "s", 0, 0, 0, 0, 0, 0, 0, 0)

    # Plot the contact element pairs as a wire-frame
    mapdl.plot("vcontact", "wireframe")

    # Stop MAPDL
    mapdl.exit()
```
Note: This code assumes that the pymapdl library is installed and available in the Python environment. Also, the code uses the `debug=True` option to enable debugging mode, which can be removed if not needed. The `plot` command uses the `vcontact` option to plot the contact element pairs, and the `wireframe` option to display the plot as a wireframe. The `contact` command uses the `genel` option to generate contact elements for general contact, and the `all` option to select all the elements for contact. The `block` command uses the `create` option to create a block, and the `mesh` option to mesh the block with tetrahedral or quadratic hexahedral elements. The `prep7` command is used to enter the pre-processor in MAPDL.