Module worksheet

Return one copy of a Sage compute process that has initialization
code run.

INPUT:
   server -- if sessions will be run via ssh on a remote account then
             this string specifies that account (passed on to the Sage
             pexpect interface).
   ulimit -- string; passed to the ulimit command before running
             the subprocess

OUTPUT:
    a pexpect interface to a local or remote copy of Sage

EXAMPLES:
    sage: S = sage.server.notebook.worksheet.initialized_sage(None,None)
    sage: S
    Sage

Set the module-scope variable _a_sage to
an initialized sage server. 

INPUT:
    server, ulimit -- strings that are passed
    to the Sage pexpect interface constructor

EXAMPLES:
The _a_sage variable is initially set to None:
    sage: sage.server.notebook.worksheet._a_sage

We call init_sage_prestart and now _a_sage is a Sage instance:
    sage: sage.server.notebook.worksheet.init_sage_prestart(None,None)
    sage: sage.server.notebook.worksheet._a_sage
    Sage

Return a Sage interface that has been initialized.

INPUT:
    server, ulimit -- strings that are passed
    to the Sage pexpect interface constructor
OUTPUT:
    -- an interface to a running copy of Sage

If the global variable multisession is true, each call to
one_prestarted_sage returns a new Sage compute instance.
Otherwise it always returns the same instance.

EXAMPLES:
    sage: sage.server.notebook.worksheet.one_prestarted_sage(None,None)
    Sage
    sage: sage.server.notebook.worksheet.multisession=False
    sage: sage.server.notebook.worksheet.one_prestarted_sage(None,None) is sage.server.notebook.worksheet._a_sage
    True
    sage: sage.server.notebook.worksheet.multisession=True

Return the relative directory name of this worksheet
with given name and owner.

INPUT:
    name -- string, which may have spaces and funny characters, which
            are replaced by underscores. 
    owner -- string, with no spaces or funny characters
    
OUTPUT:
    string
    
EXAMPLES:
    sage: sage.server.notebook.worksheet.worksheet_filename('Example worksheet 3', 'sage10')
    'sage10/Example_worksheet_3'
    sage: sage.server.notebook.worksheet.worksheet_filename('Example#%&! work\sheet 3', 'sage10')
    'sage10/Example_____work_sheet_3'

Given a string s that defines an input block of code,
if the first line begins in \samp{sage:} (or \samp{>>>}),
strip out all lines
that don't begin in either \samp{sage:} (or \samp{>>>}) or \samp{...}, and
remove all \samp{sage:} (or \samp{>>>}) and \samp{...} from the beginning
of the remaining lines.

TESTS:
    sage: test1 = sage.server.notebook.worksheet.__internal_test1
    sage: test1 == sage.server.notebook.worksheet.ignore_prompts_and_output(test1)
    True

    sage: test2 = sage.server.notebook.worksheet.__internal_test2
    sage: sage.server.notebook.worksheet.ignore_prompts_and_output(test2)
    '2 + 2\n'

Return everything after the first whitespace in the string s.
Returns the empty string if there is nothing after the
first whitespace.

INPUT:
    s -- string
OUTPUT:
    a string

INPUT:
    s -- a string like 'in=5, out=7'
OUTPUT:
    dict -- such as {'in':5, 'out':7}

The point of this function is to allow for searches like this:

\begin{verbatim}
      "ws 7" foo bar  Modular  '"the" end'
\end{verbatim}

i.e., where search terms can be in quotes and the different quote
types can be mixed.

INPUT:
    s -- a string

OUTPUT:
    list -- a list of strings