code: public static BitVector fromBigInteger(BigInteger bigInt, int size) {
  		if (bigInt == null) throw new IllegalArgumentException();
  		if (size < 0) throw new IllegalArgumentException();
  		return fromBigIntegerImpl(bigInt, size);
  
  	}
docs: Creates a {@link BitVector} from a <code>BigInteger</code>. The bits of
  the integer copied into the new bit vector. The size of the returned
  {@link BitVector} is the specified <code>size</code>. If the size exceeds
  <code>bigInt.bitLength()</code> then the most significant bits are padded
  with ones if the integer is negative and zeros otherwise. Negative values
  are recorded using 2's complement encoding.
  
  @param bigInt
  a big integer
  @param size
  the size of the {@link BitVector} to create
  @return a {@link BitVector} initialized with the bits of the big integer
  @see #fromBigInteger(BigInteger)
  @see Bits#asStore(BigInteger)