docstring, woo!
filename : String
The name of the file to open
nx : integer
The number of data elements in the x-direction
ny : integer
The number of data elements in the y-direction
nz : integer
The number of data elements in the z-direction
dtype_str : str
A valid argument for np.dtype(some_str). See read_binary.dsize attribute
headersize : integer
The size of the file header in bytes
data : ndarray
data.shape = (x, y, z) if z > 1 data.shape = (x, y) if z == 1 data.shape = (x,) if y == 1 && z == 1
header : String
header = file.read(headersize)