Solution when cannot build lxml package for installation

lxml.problem

This problems happens because there is no enough space to compile 'lxml' package,
because it needs 1gb of RAM, so we are going to create a swap area to skip this error and
fake like we have more RAM

  First, be sure you're out of memory
    dmesg | tail
  And see if you have packages needed installed
  dpkg --get-selections | grep -v deinstall > ~/packages
    cat ~/packages | grep {each package}
        - libxml2
        - libxslt1.1
        - libxml2-dev
        - libxslt1-dev
        - python-libxml2
        - python-libxslt1
        - python-dev
        - python-setuptools
        - lxml

  1 install some packages
    sudo apt-get install \
      libxml2 \
      libxslt1.1 \
      libxml2-dev \
      libxslt1-dev \
      python-libxml2 \
      python-libxslt1 \
      python-dev \
      python-setuptools
  2 create swap area
    sudo dd if=/dev/zero of=/swapfile bs=1024 count=524288
    sudo chmod 600 /swapfile
    sudo mkswap /swapfile
    sudo swapon /swapfile
  3 install lxml, use sudo if is needed
    pip install lxml
  4 when you're done, turn off swap
    sudo swapoff /swapfile